1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material containing a novel magenta dye-forming coupler.
2. Description of the Prior Art
It is known that when a silver halide photographic light-sensitive material is exposed and color-developed, a coupler reacts with the oxidation product of an aromatic primary amino developing agent to produce an indophenol, indaniline, indamine, azomethine, phenoxazine, phenazine, or other similar dye, whereby a color image is formed. In such a system, color reproduction is achieved by a subtractive color process and yellow, magenta and cyan dye images corresponding to blue, green and red light images, respectively, are formed. In general, an acylacetamide coupler or a dibenzoyl methane coupler is used for forming a yellow color image, a pyrazolone coupler, a cyanoacetyl coupler or an indazolone coupler is used for forming a magenta dye image, and a phenolic coupler such as a phenol and a naphthol is used for forming a cyan color image.
In these color photographic processes, a dye-forming coupler is either added to a color developer solution or incorporated in a light-sensitive photographic emulsion. Thus, it is possible to react the coupler with the oxidation product of the color developing agent which is formed by developing a latent image during development.
Various kinds of 5-pyrazolone derivatives are known for forming magenta color images. For example, as substituents at the 3-position of the 5-pyrazolone ring, an alkyl group, an aryl group, an alkoxy group as described in U.S. Pat. No. 2,439,098, an acylamino group as described in U.S. Pat. Nos. 2,369,489 and 2,607,788, an ureido as described in U.S. Pat. No. 3,558,319, an anilino group as described in U.S. Reissue Pat. No. 22,329 and the like are known.
These couplers must be non-diffusible in order that these couplers are prevented from diffusing into other photographic emulsion layers having sensitivities to different spectral wavelength regions and mixing with other couplers to reduce the color reproducibility by causing color mixing when these couplers are used by incorporation into a silver halide photographic emulsion during the production of the photographic light-sensitive material. For this puprose, a hydrophobic residue containing about 8 or more carbon atoms, which contributes to a reduction in the diffusibility of the coupler, as a ballasting group, is introduced into the coupler molecule.
To incorporate non-diffusible couplers into a photographic emulsion, the following three methods have conventionally been used:
1. Aqueous solution system: A non-diffusible coupler having a water-solubilizing group such as a carboxyl group or a sulfo group and being soluble in an alkaline aqueous medium is incorporated into a photographic emulsion in the form of a neutral or alkaline aqueous solution thereof and then the emulsion is neutralized with an acid.
2. Oil solution system: A non-diffusible coupler is dissolved in an organic solvent, the solution is dispersed in an aqueous medium as fine colloidal particles, and the dispersion is added to a photographic emulsion.
3. A non-diffusible coupler is melted by heating and the melted coupler is directly dispersed in a photographic emulsion or an aqueous medium.
In order to produce a green-sensitive photographic emulsion layer having excellent properties using a coupler which forms a magenta dye image employing the oil solution system, the coupler must fulfill the following conditions: that is to say, the coupler must have a high coupling reactivity with the oxidation product of a color developing agent, the magenta dye image formed must have a high fastness so that the image can be stored under severe conditions without fading, the coupler must not adversely affect the photographic emulsion and further the coupler must be readily soluble in an organic solvent employed for dispersing the coupler in a photographic emulsion and crystallize to a lesser extent in the solvent.
However, conventionally known magenta dye-forming couplers in the oil solution system show insufficient reactivity with the oxidation product of the color developing agent in the dispersed state in a photographic emulsion layer. Thus, it is difficult to obtain a green sensitive emulsion layer having excellent photographic properties using the oil solution system.
Since a magenta dye image in a color photograph using the trichromatic subtractive color process absorbs light in a wave-length region where human visual sensitivity is the highest, the light absorption characteristics of the magenta dye image are a very important factor in determining the color reproduction properties of the color photograph. In particular, it has been believed desirable to improve the sharpness of the spectral absorption curve and to reduce the secondary absorption which is specific to a pyrazolone magenta coupler image and various efforts have been made in this respect.
Also, when conventional magenta dye images formed from various magenta dye image-forming couplers are stored under high temperature and humidity conditions for a long period of time, they tend to fade, and it has been desired to improve the fastness of the dye images.